Screening discharge device for rod and ball mills



Feb. 23, 1954 M. TRESHOW SCREENING DISCHARGE DEVICE FOR ROD AND BALL MILLS Filed May 29, 1950 2 Sheets-Sheet l Awe/r454 ZPESHOW Feb. 23, 1954 M. TRESHOW 2,670,139

SCREENING DISCHARGE DEVICE FOR ROD AND BALL MILL Filed May 29, 1950 2 Sheets-Sheet 2 jA/mswrom- Maw A54 figs/10w Patented Feb. 23, 1954 s-onusmnonisunencr BALL Miohacl mmho inmfie Palisades, oans, as s-ignory'to Monolith Portland: Cement Emnpanm.

.Los Angeles nnvicnzronnoo MIIZLS" Galif aar corporation of Nevada Applicatibn Maww, 1950, sens-1N0. 165,046

This invention relates to rotary :mills '0?! the rod :mill :andrball :mill type, whichworkvupon horizontal "axes, and applies :more particularly to screening means employed at the discharge end of :grinding mills of the indicated type.

It :isza particular subject of this invention to provide .rodrand ball mills with means iorltreceiv ing, ground materials from the discharge end-I or suchwmills, classifyingthe received:materiail, and returning "to the mill those portionsnof "the dis charge which *have not sheen*sufiicientlysaround.

It iSTEilSD aniobject oftheinvent'ronito remove from the idischargezend-rofaa grinding mill suitably ground .materialsiatas early a stagezas possible murder to reduce :thehadrimposedbyiadequately groundlmaterials where -such ground. materials would otherwise. accumulate on themill untilvthey reachxa centrally located discharge lip;

:Another object of "the invention: is' to iprovside a discharge controlling structure which will-Jae effective to increase the capacity 0152a grinding mill :by reason of the fact that properly ig rou-nd materials are removed as fast as produced:

.It is a-more specific object of the: invention [to providemeans at the discharge end his grinding mill which is adapted to receive properly ground material with some accompanying oversize [mate'- rial, screen out and deliver the properly ground material, and return to the .mill' throughthe medium of the rotating action of the "mi-ll those oversizeumat'erials which have been separated :so that they may :he again subjected toy-grinding. A'further object is to provide plural-pocket means to which "oversize materials may be 'delivered fol lowing-screening, suohzpccket means serving during rotation to elevate oversize particles-and 1 mm and areed head til at the 1 struction;

Fig; 2 is a fragmentary vertical section email 2 In the arawmg:

Fig: 1' is a side elevation of a-baI-l mill embody ures hereof, portions my various inventive "to t being flbrolten enlarged scale shcwinga ortion of the screen-- inc and returning -me($1l8HlSmI, this section corresponding with a portion seen Fig.- '-l and =befling taken from-die line L 2 of Fig. "3-;

I mhe drawings iilustrate:..a moreori'less-convenduring passage over or adjacent vtopcenter-to drop them into re the mill.

A further object of theinventioniis .to provide urn means leading; -back- .into

appropriate feed means 'by which cement clinker or similar feed material being supplied" to .a grinding mill may be substantially continuously fed to themill'so that the feed may keep up with the .rapid discharge .of the ground material-by 1 indicated classifying. device, even Where batches of feed material are.

way of the previously required to be brought :up 'to'the mill 'from remote loading locations.

Other objects of the invention together with the various features of construction thereof will become apparent to "thoseskilledihthe-artiupon;

reference to the; iollowinaspecincation and the aprirtidetrwith flanges M which tactian'eictmaximinn iengvth.

accompanying .d'rawimgns wherein vc'ertaiz'i embodiments of th invention are illustrated;

Fig." 3 is a transverse; vertical" section and le vation as indicated by the line 3 of Fig. 1; and f Fig; 4 is a'vertical transverse section taken: on the line 4-Il of'li!ig.1.

tional :ba'ill m-ill working' upon a horizontal axis and :compnising-a' cylindrical shell Ill which conventionatly receives a quant'ty of grinding balls B,,rthe::snel1 in having a discharge :head 122 at one other end. shell in :is showna's hem'gprovided with pairs of rails lfinsuppoited upon flanged wheels it carried uponanaxlesliiiicurnalled dnxappropriatelbearings l 8. fln'the' particulamtmmillustrated; the raiis"l*5 rare generally in the aformwof conventional railroad mails ha ving meads an, swehs 2d and flanges or bases 22 "which are-rinsetinto annular grooves outer "wall ot the':shell 1:0; The" 23' termed omthe wheels 1:6 mayibsstandard railroad rear wheels engage sides-of the rails 1:5 ,imsuchaimanneras to" prevent axial shiit' tot themitl; 'The contactingfaces of the rail heads 20' and the treadswof thewheels com form with one another sothat therlines "of con- "The mill is rotated through themed-mm 03' a drive shatt d ingS 28iv For' theipurposeiotclassifying rial leaving the mill through l2 iand alsc introducing theiloadeof rialz'as rapidly waslpossihle, the discharge FhBEdilZ is: :providedhwiith a iplurality er charge :npenings Bll; ipreierahly circular serieseas zbest; iindicatedand disposed :intermediatelyof of the" such will ialndzthei :head :I 2 opening. 34- q-thtougih may eventual-Hy :lte' returned These l? oarniedfiin appropriate: bearea at the bottom of v (Fig; 1.

head vl2 around each of the openings is a away to illustrate internal con- The :a wing ear 725 secured aroundi-th'e witind-raiaeiiiion-fl-fi:mounted on I thezground imatethe "dischargeihead ound mate-' arranged int-1athe "peripheries wand a'zcentral" which oversized material 4 openings 3.0 are provided with appropriate screening material, such; as typical screens .indicatedatthe top ofvt ni'gzl,iengratingsdsisucntas indicated-in .,.-Secured' againsti thecnuter ace, of" =the-idischarge tubular, preferably cylindrical screening device 34. The screens 32 and gratings 33 are adapted to pass not only material which has been sumciently ground but also some material that is slightly oversize, while serving at the same time to prevent the passage of materials which are greatly oversize and-similarly to prevent the passage of the grinding balls B. The cylindrical 34 thus serve as classifiers which act to remove appropriately ground materials as quickly as pos-' sible, the initial discharge taking place below the uppermost grinding balls.

The oversize material which is passed by the screen 32 or gratings 33, but is too coarse to be passed by the screening devices 34, is discharged from the outer ends of the cylindrical screening devices 34 into respective pockets 4!! whose peripheral walls 4! and outer side walls 42 may be imperforate except for peepholes 43 as indicated. These pocket members 43, which are somewhat pear-shaped with rounded outer ends and truncated inner ends, are provided with flanges at their inner ends, which are bolted as indicated at 45 to a correspondingly flanged, circular, central member generally indicated at 45. The member 45 has an outer wall 41 which is connected by means of throat-forming radiating partitions 48 to aninner wall 49 of annular shape and in turn connected with an inwardly extending solid walled, cylindrical sleeve 50 fixed at its inner end to the outer face Of the discharge head 1'2 about the central opening 3!. The inner ends of the partitions 48 are connected to a conical, inwardly directed, deflecting wall 52 which feeds oversized materials, falling from elevated pockets 40 approaching top center position, into the outer end of the cylindrical sleeve 50 which serves as a conductor for such oversized materials and is provided with an internal screw blade 54 that acts to advance the received materials inward through the opening 3| to the interior of the mill. An inwardly directed flaring lip 55 feeds such oversized material back into the mill an appropriate distance from the discharge openings 30.

The rotating screening, classifying, and returning devices 34, 40, and 50 are enclosed by a stationary hood so connected with the top of the previously mentioned hopper 35 and its discharge chute 35, the inner wall 6| ofthe hood 60 being in the form of a flange which engages behind an annular flange 62 carried by the outer face of the discharge head 12. These flanges BI and 52 provide a sufliciently tight joint between the rotating and nonrotating parts. For the purpose of introducing an adequate supply of water to the interior of the mill, the outer wall 63 of the hood 6!! is provided with an appropriate water supply pipe 64 which extends through an opening in the apex of the conical deflecting wall 52, whereby to inject a water stream centrally through the sleeve 50 and its spiral screw blade 54 into the interior of the mill. In wet mill operations, this water supply'will aid in pre-- venting clogging of the device'by moist m'aterial being handled. In dry water supply w111 or course be' cut -off. f

mill operations, the

From the foregoing description, it will be apparent that ground materials passing through the screens 32 and gratings 33 at the discharge openings 3B are appropriately sifted by the screening devices 34 as the mill rotates, the desired finely ground materials passing through the screening devices 34 and falling into the hopper 35 at the bottom of the hood 6!], the annular rotating flange 62 serving to deflect materials passing through the adjacent ends of the screening devices 34. By providing for passage of materials through the screens 3?. or gratings 33 which are somewhat oversize, the load of adequately ground material in the mill may be more rapidly and efiiciently reduced, the accompanying oversized materials being subsequently returned for further grinding. As an illustration of these relationships, the screens 32 or gratings 33 may pass material as large as inch, whereas screening devices 34 may pass material no longer than 5 inch.

By employing the rails l5 and flanged wheels It for supporting the mill, as previously described, the discharge end of the mill is left unobstructed so that the present form of screening and discharge means may be readily placed and used which would be impossible with trunnion supports at the axis of the mill.

For the purpose of feeding unground mate- .rial to the mill I may employ the portable chute device illustrated at the left of Fig. 1. This comprises a framework 35 carried upon wheels 65 and supporting a discharge chute 68 which is normally disposed below any materials source 63 and is adapted to be directed into an intake opening It in the feed head 14 of the mill. The wheels 66 travel upon appropriate rails 12 carried upon any suitable substructure '14. Thus the framework 65 and the chute 58 may be moved .away from the feed opening in for access to the interior of the mill whenever necessary.

Inasmuch as other variations of the generic invention disclosed will become apparent to those skilled in this art, it is intended to cover all such modifications as fall within the scope of the patent claims.

I claim as my invention:

1. In a discharge head structure for a grind ing mill, the combination of: a head adapted for disposiiton in a vertical plane, said head having a central opening and a plurality of discharge openings dispcsed between said central opening and the periphery of said head; screen means disposed across the respective discharge openings; a plurality of cylindrical screening devices connected to said head and disposed on horizontal axes about the respective discharge openings to receive from said screen means and directed outward from said head and providing screen surfaces throughout their peripheries; a plurality of receiving pocket means disposed at and connected respectively with the outer ends of said tubular cylindrical screening devices to receive oversize materials from such devices and having discharge means to dump such oversize materials during rotation: a tubular return device connected to said head about said central opening to receive dumped. oversize materials from said pocket means and feed such oversize. materials through said central opening back into the mill; and connecting means leading from portions of said, pockets directed toward. the axis; of said head to said return device m supplying oversize material from said tubular screening devices to said return device. and thence through said central opening.

2. A combination as in claim 1 wherein partition means are provided between said pocket means whereby to return oversize material to said return device as said pockets approach a top center position above said return device.

3. In a combination in a discharge head construction for a grinding mill rotatable on a substantially horizontal axis: a vertical discharge head having a return opening disposed adjacent its axis of rotation and a plurality of discharge openings disposed in a series around said axis between said return opening and the periphery of the .head; a plurality of tube-like horizontal screening devices mounted on said head" and disposed respectively about said discharge openings to receive therefrom at one end and open at their opposite ends to pass radially therethrough adequately ground particles while separately discharging oversize particles horizontally therefrom at their open ends; a plurality of pockets disposed horizontally beyond said screening devices and communicating respectively with the open oversize discharge ends of said screening devices, said pockets having discharge throats extending radially inward to dump oversize particles when said pockets are successively moved by mill rotation to elevated positions; and a return device communicating with said throats and with said return opening to pass oversize particles through said return opening into said mill.

4. A combination as in claim 3 wherein said return device includes sloping deflector means at the inner ends of said throats and a conveyor tube leading from said deflector means to said return opening.

5. A combination as in claim 4 including conductor means communicating with said conveyor tube on the opposite side of said return opening and head and extending a substantial distance beyond said opening to feed returned material back into the mill beyond said discharge openings.

MICHAEL TRESHOW.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 813,903 Lindhard Feb. 27, 1906 964,629 Fasting July 19, 1910 1,368,739 Lindhard Feb. 15, 1921 1,414,603 Taylor May 2, 1922 1,591,916 Lindhard July 6, 1926 1,670,005 Pratt May 15, 1928 1,787,788 Kueneman Jan. 6, 1931 FOREIGN PATENTS Number Country Date 84,325 Germany Apr. 28, 1895 420,049 Germany Oct. 15, 1925 499,880 Germany June 14, 1930 

